Hi kpilling,
It has been my experience that when you dine in Paris you dine for the evening. The table is yours for as long as you like and unlike in the USA you have to ask for the check. I don't think sharing the maine course is "acceptable." Part of the dining experience is just enjoying the evening.
Happy travels!

Hub and I have asked to split a starter and/or dessert but get our own entrees. Most places didn't mind when we did this. Of course, we take notes of everything we eat (I am busily copying from the menu!) so maybe they thought we were food critics!